JPH07294307A - Volumenometer - Google Patents

Abstract

PURPOSE:To enable measuring of even the capacity of a soft container by imposing an alternating volumetric change on a first container and a second container covering a container to be measured, both coupled communicating with the container to be measured, to detect a change in the pressure within an acoustic system. CONSTITUTION:A speaker 6 is mounted on a partition 4 separating first and second containers. When an alternating drive signal such as sine wave is applied to the containers through terminals 8 and 9 from a signal generator 16, a diaphragm 7 of the speaker 6 is displaced so that the individual containers are subjected to a differential volumetric change. A microphone 12 is mounted on the partition 4 and an output e2 thereof is transmitted to a signal processor 15 via a terminal 17 and likewise, a microphone 11 is mounted on the first container to transmit an output e1 to the signal processor 15. The signal processor 15 performs a precise measurement of a capacity based on the signals e1 and e2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a volume meter for measuring the volume of a container having a complicated shape, and more particularly to a volume meter of the type utilizing the pressure change of gas in the container.

[0002]

2. Description of the Related Art As one method for measuring the volume of a container having a complicated shape, a sound source such as a speaker gives an alternating volume change to a space inside the container to adiabatically expand the gas therein. There is a method of obtaining the volume of the container from the pressure change at that time.

As one of the measuring methods of this type, the applicants have disclosed a reference container and a container to be measured in Japanese Patent Publication No. 2-33084 and Japanese Patent Application Laid-Open No. 5223616 (hereinafter, these two are referred to as prior inventions). An alternating volume change is differentially given to both of the two, and the magnitude of the alternating volume change is calculated from the ratio of the magnitudes of the pressure changes of the gas in these containers that occur at that time, that is, the ratios of the sound pressures. An acoustic volume meter is shown that measures the volume independently of the above, and is not affected by the static pressure of the gas in the container.

[0004]

In the device of the above-mentioned invention of the prior application, the volume of a hard container such as a glass bottle can be precisely measured, but in the case of a soft container such as a thin plastic bottle, the wall of the container has an internal pressure. Since it vibrates in response to the change, it causes a large error in the volume measurement value.

An object of the present invention is to provide an acoustic volume meter capable of measuring the volume of the soft container as described above.

[0006]

According to the volume meter of the present invention, there is provided a first container in which containers to be measured are connected in communication with each other, a second container for covering the containers to be measured, and the first and second containers described above. It consists of means for differentially giving an alternating volume change to the container and means for detecting the pressure change inside the acoustic system consisting of the above-mentioned container and the like, and the volume of the container to be measured is obtained from this detected pressure change. It is like this.

[0007]

[Operation and effect] The measuring principle of this volume meter is based on the premise that the first and second containers are given a volume change with equal absolute values and opposite signs. During measurement, when the wall of the container to be measured vibrates due to pressure change and the volume of the first container is compressed by a certain volume, the volume of the second container expands by the same volume. Therefore, the precondition of the measurement that the two containers are given a volume change of equal absolute value and opposite sign is established regardless of the vibration of the walls of the containers, and a precise volume measurement can be performed.

[0008]

First Embodiment In FIG. 1, 1 is a first container having a volume of V ₁ and 3 is a container to be measured whose volume V _X is connected to the inside of the container 1 through a communication hole 10. Therefore, the total volume of the container 1 including V _X is (V ₁
+ V _X ). Reference numeral ₂ covers the measured container 3 with a second container having a volume of V ₂ , but its internal volume is (V ₂ −V _X −V _T ) because the container 3 projects inside. . Here, V _T is the tare volume of the container 3, that is, the volume of the material forming the container 3.

The upper surface 4 of the container 1 serves as a partition that separates the containers 1 and 2, and a speaker 6 is attached to this partition as a means for giving an alternating volume change to these containers and a signal generator. When an alternating drive signal such as a sine wave is applied from 16 through terminals 8 and 9, diaphragm 7 of speaker 6
Is displaced, and the volumes of the containers 1 and 2 are differentially changed. The partition wall 4 is also provided with a microphone 12 as a means for detecting a pressure change inside the container 2, and its output e ₂ is passed through a terminal 17 to a signal processing device 15 such as a computer.
Sent to. Similarly, a microphone 11 is attached to the container 1 as a means for detecting a pressure change inside the container 1, and its output e ₁ is sent to the signal processing device 15. The signal sent from the signal generator 16 to the signal processing device 15 through the lead wire 18 is a synchronizing signal used when the signals e ₁ and e ₂ are analog-to-digital converted and taken in at 15, but is independent by a clock inside the device 15. If the analog-to-digital conversion is performed on, the sync signal is unnecessary.

Reference numeral 5 is a capillary tube for balancing the static pressure inside the containers 1 and 2, but for the alternating pressure change provided by the speaker 6, that is, the sound of the measurement frequency, the gas in the capillary tube 5 is changed. The resistance due to viscosity is very large,
Acoustically, 5 is equivalent to being closed. 13, 1
4 is a similar capillary tube, these are containers 1 and 2 respectively.
Although the static pressure inside is equilibrated with the atmospheric pressure outside, 13 and 14 are unnecessary if the capillary tube 5 is provided. Again 1
If there are 3 and 14, 5 is unnecessary. Further 5, 13, 1
Even without the 4, these capillaries are not essential to the invention, since the static pressure inside the containers 1, 2 is normally balanced by the external atmospheric pressure due to the gaps in the assembly of the device.

Now, assuming that the speaker 6 is driven by the signal from the signal generator 16 and as a result the diaphragm 7 is displaced and the inner volume (V ₁ + V _X ) of the container 1 is expanded by a volume of ΔV _S , The internal volume (V ₂ −V _X −V _T ) of the container 2 is compressed by ΔV _S. That is, ΔV _S is applied to containers 1 and 2.
The volume change is given differentially. Further, at this time, the container 3 to be measured is changed by the pressure change generated inside these containers.
The wall of the container 1 is displaced, and the inner volume (V ₁ + V _X ) of the container 1 is ΔV _B
When the volume of the container 2 is expanded, the inner volume of the container 2 (V ₂ −V _X
-V _T ) is compressed by ΔV _B. Here, the pressure changes inside the containers 1 and 2 are -ΔP ₁ and ΔP ₂ , respectively,
Also

[0012]

[Equation 1]

Then, from the relational expression of the adiabatic change of gas,

[0014]

[Equation 2]

[0015]

[Equation 3]

[0016] Here, P is the average static pressure of the gas inside the containers 1 and 2, and γ is the specific heat ratio of the gas. From the above two formulas

[0017]

[Equation 4]

[0018] here

[0019]

[Equation 5]

[0020]

[0021]

[Equation 6]

The following relational expression is obtained. V in the above formula
₁ and V ₂ are constant values, and V _T can be separately known by measuring the weight of the container 3 to be measured and dividing it by the specific gravity of the material thereof.
The volume V _{X of the} container 3 to be measured can be obtained from this.

FIG. 2 is an electrical equivalent circuit of the acoustic system of the apparatus shown in FIG. Vessels 1 and 2 are represented by volumes C ₁ and C ₂ , respectively, whose volume is proportional to their volumes V ₁ and V ₂ . C _X is a volume representing the volume V _{X of the} container 3 to be measured, but since the inner volume of the container 1 is (V ₁ + V _X ),
C _X is connected in parallel with C ₁ . The internal volume of the container 2 is (V
₂₋ V _X −V _T ), a virtual negative capacitance −C _X is connected in parallel with C ₂ . Further, a virtual negative capacity −C _T representing the tare volume V _T of the container 3 to be measured is also connected in parallel with C ₂ . The speaker 6 is represented by an AC power supply SPK and Z ₀ representing its output impedance.

The action of the wall of the container 3 to be oscillated by the change in internal pressure is represented by the capacitance C _B having a size proportional to the compliance of the wall.
In this device, since C _B is connected in parallel with the power source SPK, it does not affect the measured value of C _X. On the other hand, when measuring the volume of the container by the device of the invention of the previous application,
Since the wall of the container is in contact with the outside atmosphere, the capacity C _B representing the compliance of the wall is C representing the volume of the container.
It will be connected in parallel with _X , which will cause an error in the measurement of C _X.

[0025]

[Second Embodiment] FIG. 3 shows an apparatus according to an embodiment mainly intended for inspecting a large number of mass-produced containers having substantially the same volume. First container 1 volume V _1, the container to be measured 3 in volume V _x, the container 2 of the volume V ₂ covering the speaker 6 to give differentially volume change in the container 1 and 2 and the device of FIG. 1 Is the same. 21
Is a communication tube having a tip end portion 23 screw-coupled, which communicates with the inner spaces of the containers 1 and 2 and is located inside the pipe at a distance L ₂ from the end toward the container 2 and a distance L ₁ from the other end. A microphone 20 for detecting pressure change is attached. Two
Reference numeral ₂ is a microphone for detecting a pressure change inside the container 2, and its output e ₂ is sent to a signal processing device 25 via a terminal 28. Similarly, the output e ₀ of the microphone 20 is sent to the signal processing device 25 via the terminal 29. Incidentally, when [Delta] V _P becomes the volume of gas through the communicating pipe 21 flows into the container 2, since also [Delta] V _P becomes the volume of the gas from the container 1 flows out through 21, an absolute value in the container 1 and 2 is equal opposite sign volume The assumption that change is given holds even if there is a communication pipe.

The pressure change at the end of the communication pipe 21 toward the container 2 is a pressure change ΔP ₂ inside the container 2, and the pressure change at the other end is a pressure change inside the container 1 −ΔP ₁ . Assuming that the internal cross-sectional area of the communicating pipe 21 is uniform, the distribution of pressure change in the pipe is from the pipe end to the distance L ₂ from ΔP ₂ to −ΔP _1.
It changes linearly with respect to. On the other hand, ΔP ₁ and ΔP ₂
Because there is a relationship shown in (Equation 4)

[0027]

[Equation 7]

In case of, the output e of the microphone 20
₀ becomes 0. Even if the internal cross-sectional area of the communication pipe 21 is not uniform, the fact that the change in pressure inside the pipe becomes 0 is the same in the middle of the pipe.

In order to measure the volumes of a large number of containers having substantially the same volume, one of the volumes V _R is precisely measured using water or the like, and this is used as a reference container in the apparatus of FIG. Instead of the above, turn the communication pipe tip 23 in that state to change L ₂ and output e of the microphone 20.
₀ is adjusted to be 0. After that, when the reference container is removed and another container is attached as the container to be measured 3, a microphone output e ₀ having a size corresponding to the difference (V _X −V _R ) between the volume V _X and the reference container volume V _R. Occurs, the value of V _X with reference to V _R can be obtained.
The relationship between the magnitude of the signal e ₀ and (V _X −V _R ) is
Providing a second reference container with different known volume and V _R, defined by such to try to measure the volume.

FIG. 4 shows an example of the internal structure of the signal processing device 25. The output e _{0 of the} microphone 20 is amplified by the amplifier 251, and then synchronously rectified by the synchronous rectifier 253. The output e _{2 of the} microphone 22 is amplified by the amplifier 252 and then given to 253 as a synchronizing signal. Synchronous rectifier 2
At 53, the magnitude of the component coherent with e ₂ of the signal e ₀ is detected, and its output signal is given to the display 255 to display the difference between V _X and V _R. The output of the amplifier 252 is also rectified by the rectifier 254 to be a DC signal having a magnitude proportional to the amplitude of the signal e ₂ , and is given to the signal generator 26 through the lead wire 27 so that the amplitude of the pressure change ΔP ₂ inside the container 2 is increased. 26 to speaker 6 so that it is constant
Control the magnitude of the drive signal applied to the. However, when all the containers 3 to be measured have substantially the same volume, the above control is not essential because the amplitude of ΔP ₂ becomes almost constant when a drive signal of a constant magnitude is applied to the speaker 6.
Further, the synchronous signal supplied to the synchronous rectifier 253 can be replaced by the drive signal output from the signal generator 26, and thus the microphone 22 is not essential.

In the above description, the reference container is attached and the output e _{0 of the} microphone 20 is adjusted to be 0. At that time, the communication pipe tip 23 is turned to change the ratio of L ₁ and L _2. Is one of the adjusting means, and as is clear from (Equation 7), the signal e ₀ can be reduced to 0 by varying one or both of the volume V _{1 of} the container ₁ and the volume V ₂ of the container 2. Can be Also, using one of a large number of containers of approximately the same volume as the reference container makes it possible to increase the slight volume difference because the microphone output e ₀ is small when measuring the volumes of the other containers. The reason is that it can be accurately identified. Therefore, except that it is disadvantageous in terms of measurement accuracy, the volume V _R of the reference container can be freely selected. For example, without using the reference container, V _R = 0, that is, the communication hole 10 is closed. May be used as a reference.

Furthermore, even if the signal e ₀ is not ₀ when the reference container is attached and has a certain size, the change in e ₀ when the reference container is replaced with the measured container is the reference container. because corresponds to the volume difference of the container to be measured (V _X -V _R), can be obtained V _X with respect to the V _R. In short, the essence of using the communicating pipe is that there is a zero point where the pressure change in the pipe becomes 0, and its position is determined only by the volume of the container, as shown in (Equation 7). Therefore, it is advantageous in terms of measurement accuracy to perform volume measurement by using this stable pressure change near the zero point.

[Brief description of drawings]

FIG. 1 is a volume meter according to a first embodiment of the present invention.

2 is an electrical equivalent circuit of the acoustic system of the device of FIG.

FIG. 3 is a volume meter according to a second embodiment of the present invention.

4 is an example of an internal structure of a signal processing device of the device of FIG.

[Explanation of symbols]

1 1st container of volume V ₁ 2nd container of volume V ₂ 3 Container for measurement of volume V _X 4 Partition 5 Capillary tube 6 Speaker 7 Speaker diaphragm 8, 9 Terminal 10 Communication hole 11, 12 Microphone 13, 14 Capillary Tube 15 Signal Processor 16 Signal Generator 17 Terminal 18 Conductor 20, 22 Microphone 21 Communication Tube 23 Communication Tube Tip 25 Signal Processor 26 Signal Generator 27 Conductor 28, 29 Terminal 251, 252 Amplifier 253 Synchronous Rectifier 254 Rectifier 255 display

Claims (2)

[Claims] 1. A first container in which the containers to be measured are connected in communication with each other, a second container for covering the containers to be measured, and an alternating volume change differentially applied to the first and second containers. And a means for detecting a pressure change inside each of the first and second containers, and determining the volume of the container to be measured by the ratio of the two detected pressure changes. Characteristic volume meter. 2. A first container in which the containers to be measured are connected in communication with each other, a second container covering the containers to be measured, and an alternating volume change differentially applied to the first and second containers. And a means for providing communication between the first and second containers, and means for detecting a change in pressure inside the communication tube.
A volume meter characterized in that the volume of the container to be measured is determined from the detected pressure change inside the communication pipe.